Effect of Anisotropy of Masonry on the Behaviour of Unreinforced and Confined Masonry Walls Under Ground Motion

This paper presents the numerical test results of the effect of anisotropy on the behaviour of unreinforced and confined masonry walls under horizontal harmonic ground acceleration. Two-storey masonry walls with different lengths (3, 6, 12 m) are analysed. The wall foundations are supported on a rigid base, with possibility of lifting. A non-linear macro model of masonry is used. Cases of strong masonry (high strength and stiffness) and weak masonry (low strength and stiffness) are analysed. Different coefficients of anisotropy of masonry ca (0.2, 0.4, 0.6, 1.0) are considered. The excitation period is taken to correspond to the fundamental period of the individual elastic wall. Horizontal displacements at the top of the walls, vertical stresses in masonry and concrete at the bottom of the walls and stresses in the longitudinal bars at the bottom of the vertical ring beams are shown for each analysed case. It is concluded that the ultimate bearing capacity and deformability of walls, as well as stresses in masonry, concrete and reinforcement under dynamic excitation significantly depend on the anisotropy of masonry. It is also concluded that, with the same coefficient of anisotropy, the behaviour of masonry walls depends on its type (unreinforced, confined), height to length ratio (0.5, 1.0, 2.0), and the quality of masonry (strong, weak).